Description: The connector -/\ is symmetric. (Contributed by Jeff Hoffman, 17-Nov-2007) (Proof modification is discouraged.) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | nic-swap | |- ( ( th -/\ ph ) -/\ ( ( ph -/\ th ) -/\ ( ph -/\ th ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nic-id | |- ( ph -/\ ( ph -/\ ph ) ) |
|
| 2 | nic-ax | |- ( ( ph -/\ ( ph -/\ ph ) ) -/\ ( ( ta -/\ ( ta -/\ ta ) ) -/\ ( ( th -/\ ph ) -/\ ( ( ph -/\ th ) -/\ ( ph -/\ th ) ) ) ) ) |
|
| 3 | 1 2 | nic-mp | |- ( ( th -/\ ph ) -/\ ( ( ph -/\ th ) -/\ ( ph -/\ th ) ) ) |